Rhodium cationic complexes using dithioethers as chiral ligands. Application in styrene hydroformylation

Article abstract of DOI:10.1016/S0022-328X(97)00692-X

Addition of the dithioethers ( - )-DIOSR₂ (R = Me, ⁱPr) (2,3-O-isopropylidene-1,4-dimethyl (and diisopropyl) thioether-L-threitol) to a dichloromethane solution of [Rh(COD)₂]ClO₄ (COD = 1,5-cyclooctadiene) yielded the mononuclear complexes [Rh(COD)(DIOSR₂)]ClO₄. X-ray diffraction methods showed that the [Rh(COD)(DIOSⁱPr₂)]ClO₄ complex had an square-planar coordination geometry at the rhodium atom with the ⁱPr groups in anti position. Cyclooctadiene complexes react with carbon monoxide to form dinuclear tetracarbonylated complexes [(CO)₂Rh(μ-DIOSR₂)₂(CO) ₂](ClO₄)₂. [Rh(COD)(DIOSR₂)]ClO₄ are active catalyst precursors in styrene hydroformylation at 30 atm and 65°C which give conversions of up to 99% with a regioselectivity in 2-phenylpropanal as high as 74%. In all cases enantioselectivities are low.

Full text of DOI:10.1016/S0022-328X(97)00692-X

Journal of Organometallic Chemistry 559 (1998) 23–29
Rhodium cationic complexes using dithioethers as chiral ligands.
Application in styrene hydroformylation
a
A. Orejo´n a, A.M. Masdeu-Bulto´ , R. Echarri b, M. Die´guez a, J. Fornie´s-Ca´mer a,
C. Claver a,*, C.J. Cardin c
a Departament de Qu´ımica F´ısica i Inorga`nica, Uni6ersitat Ro6ira i Virgili. Pl. Imperial Tarraco 1, 43005, Tarragona, Spain
b Uni6ersite´ Abdelmalek Essaadi, De´partement de Chimie, Te´touan, Morocco
c Department of Chemistry, The Uni6ersity of Reading, White Knights, P.O. Box 224, RG6 6AD, Reading, UK
Received 9 August 1997; received in revised form 16 October 1997
Abstract
i
Addition of the dithioethers (−)-DIOSR2 (R=Me, Pr) (2,3-O-isopropylidene-1,4-dimethyl (and diisopropyl) thioether-L-thre-
itol) to a dichloromethane solution of [Rh(COD)2]ClO4 (COD=1,5-cyclooctadiene) yielded the mononuclear complexes
[Rh(COD)(DIOSR2)]ClO4. X-ray diffraction methods showed that the [Rh(COD)(DIOSiPr2)]ClO4 complex had an square-planar
i
coordination geometry at the rhodium atom with the Pr groups in anti position. Cyclooctadiene complexes react with carbon
monoxide to form dinuclear tetracarbonylated complexes [(CO)2Rh(v-DIOSR2)2(CO)2](ClO4)2. [Rh(COD)(DIOSR2)]ClO4 are
active catalyst precursors in styrene hydroformylation at 30 atm and 65°C which give conversions of up to 99% with a
regioselectivity in 2-phenylpropanal as high as 74%. In all cases enantioselectivities are low. © 1998 Elsevier Science S.A. All rights
reserved.
Keywords: Rhodium; Dithioether; Hydroformylation
1. Introduction
chelating or macrocyclic thioethers [3]. The two lone
electron pairs allow the thioether to coordinate to the
metal either in the terminal or the bridging position,
providing in this case dinuclear complexes [3].
Cationic rhodium and iridium complexes with the
general formula [M(diene)Ln]+ n=2 or 3 are homoge-
neous hydrogenation precursor catalysts since under
hydrogen the diene is hydrogenated to generate the
reactive ML2+ fragment [1]. This is an excellent catalyst
and it has several unusual properties partly because of
its ionic character. Interestingly, this cationic system is
active for a large number of donor ligands L. The
chemistry of cationic rhodium complexes has been ex-
tensively studied and the asymmetric induction of chiral
bidentate phosphorus ligands has been discussed in
depth [2].
The first thioether rhodium(I) complexes of the type
[Rh(diolefin)L2]+ were reported in 1978 using cy-
cloocta-1,5-diene (COD) or norbornadiene (NBD) as
the diolefinic ligand and 1,4-dithiacyclohexane as the
sulphur ligand [4]. Another example of a [Rh(dio-
lefin)L2]+ complex with tetrafluorobenzobarralene as
the diolefin and tetrahydrothiophene (THT) as the sul-
phur ligand was reported in 1980 [5]. Since 1983, sev-
eral works have appeared about the preparation and
reactivity of this type of cationic complexes where the
diolefin is COD or NBD and L is THT, trimethylene
sulphide (TMS), SMe2, SEt2 or dithioethers such as
1,4-dithiacyclohexane (DT), MeS(CH2)3SMe and
(tBuS)(CH2)3(tBuS) [6]. More recently, the atropoiso-
Thioethers, R2S, are considered to be relatively weak
donors and poor acceptors, but binding is stronger with
* Corresponding author.
0022-328X/98/$19.00 © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(97)00692-X

24
A. Orejo´n et al. / Journal of Organometallic Chemistry 559 (1998) 23–29
meric dithioethers BINASR2 and BIPHESR2 (Fig. 1)
have been used as ligands in the synthesis of cationic
[Rh(COD)(dithioether)]ClO4 complexes. These com-
plexes have proved to be catalyst precursors in styrene
hydroformylation which provide high catalytic activity
and regioselectivity, although the stereoselectivity did
not exceed 20% of enantiomeric excess [7].
Using the well known chiral diphosphine (+)DIOP
((2S,3S)-2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis
(diphenylphos phino)butane) as a model, related chiral
chelating sulphoxide ligands have been used to prepare
rhodium and ruthenium catalyst hydrogenation systems
[8]. More recently dinuclear rhodium complexes have
been prepared with the related dithiolate (−)DIOS2−
(2,3-O-isopropylidene-1,4-dithio-L-threitol) as chiral
bridging ligand and used in homogeneous styrene hy-
droformylation [9].
Fig. 2. Chiral ligands DIOSR2.
In this work, the [Rh(COD)(dithioether)]A com-
plexes were prepared by adding the corresponding
dithioether ligand DIOSR2 (R=Me, iPr) to
a
dichloromethane solution of [Rh(COD)2]ClO4 (Eq. (1)).
After stirring, the brown solution turned yellow and the
addition of diethyl ether caused the precipitation of the
moderately air-stable products for which the elemental
analyses of C, H and S correspond to the stoichiometry
{[Rh(COD)(dithioether)]ClO4.1/2 CH2Cl2}n.
In the same conditions, [Rh(COD)2]ClO4 was not
seen to react with the dithioether DIOSPh2. In an
attempt to favour COD substitution by hydrogenation,
H2 was bubbled through the reaction mixture but no
reaction was observed.
In order to investigate the chemistry and catalytic
activities of cationic rhodium complexes containing re-
lated dithioether chiral ligands DIOSR2, R=Me, Pr,
i
Ph (Fig. 2) we believed it would be of interest to study
the preparation, characterization and reactivity of com-
plexes of the type [Rh(COD)(dithioether)]+ containing
these ligands. The dithioether ligands were prepared
during a project about metal complexes containing
sulphur derivatives to be used in catalytic processes.
The application of the cationic rhodium complexes as
catalyst precursors in the styrene hydroformylation is
also reported.
[Rh(COD)2ClO4+DIOSR2“
“[Rh(COD)(DIOSR2)]ClO4+COD
2. Results and discussion
R=Me
R=iPr
1
2
(1)
2.1. Preparation of [Rh(COD)(dithioether)]A
(A=ClO−4 ) complexes
The FAB mass spectrum shows the heaviest ion at
m/z=433 for complex 1 and at m/z=489 for complex
2 which is indicative of mononuclear complexes where
the anion ClO4− has been lost.
One way of preparing cationic complexes of the type
[M(diene)Ln]+ is to treat the dimer compounds [M(v-
Cl)(diene)]2 with an equimolecular amount of the silver
salt and the corresponding ligand L [1]. An alternative
and convenient method is to displace a COD molecule
(1,5-cyclooctadiene) from the air stable, starting mate-
rial [M(COD)2]A [10].
The IR spectrum shows two strong bands at 1096
and 625 cm−1 for complex 1 and at 1100 and 620 cm−1
for complex 2 which are characteristic of the non
coordinated ClO4− anion in cationic rhodium
complexes.
1
The H- and 13C-NMR data for both complexes 1
1
and 2 were assigned using HETCOR H–13C experi-
1
ments and complex 2 also required COSY H–1H and
DEPT experiments.
The 1H-NMR spectrum for complex 1 has one singlet
signal at 1.45 and 2.38 ppm which shows the equiva-
lence of the methylenic protons of the coordinated
ligand CH3–S and O–C(CH3)2 respectively. The
olefinic –CHꢀ protons of the coordinated COD appear
as two multiplet signals at 4.65 and 4.55 ppm.
This distribution of signals is in agreement with a C2
symmetry of the molecule caused by the chiral ligand,
which can be seen in Fig. 3.
Fig. 1. Atropoisomeric dithioethers BINASR2 and BIPHESR2.

A. Orejo´n et al. / Journal of Organometallic Chemistry 559 (1998) 23–29
25
Fig. 3. Molecular symmetry of the catonic complexes [Rh(COD)2]+
.
In accordance with this symmetry, the methylenic
protons h and i to the dithioether group –CH j–
CHiHh–S are diastereotopic and appear as a complex
second order ABX system at room temperature centred
at 3 ppm. At 40°C this signal is resolved in two, at 3.12
and 3.27 ppm (Fig. 4). Both signals (corresponding to
Hh and Hi) have a geminal coupling constant of 12 Hz.
Taking into account that the coupling constants
be found for the anti invertomer in which the methyl
protons are related for a C2-geometry and only one
1
signal will appear in the H-NMR spectra. As is shown
by the 1H-NMR spectra, either one of the two anti
diastereoisomers is present in solution or there is a
rapid exchange between them both which is not de-
tected on the NMR time scale.
In order to detect the presence in solution of other
conformations of the seven membered dithiother ring
2
2JHax–Hax are greater than JHax–Heq, the signal at 3.12
ppm (2JH–H=9 Hz) was assigned to the Hh methylenic
proton and the other signal at 3.27 ppm (2JH–H=3 Hz)
was attributed to Hi protons coupled with H j in an
axial–equatorial manner.
As expected, two resonances were observed at 31.54
and 30.69 ppm in the 13C-NMR spectra of complex 1
for the olefinic coordinated COD carbons. The rest of
the 13C-NMR signals were in accordance with a C2
symmetry.
Dithioether ligands create two asymmetric centres
when they coordinate to a metal atom. As DIOSR2 are
chiral ligands with a fixed SS configuration, there are
three diastereoisomers possible for the new complexes
with the configurations SSRR, SSSS and SSRS (Fig. 5)
The diastereoisomers SSRR and SSSS correspond to
the anti invertomer and the SSRS to the syn [11]. The
syn invertomer will give two signals for the methyl
protons of the DIOSMe2 whereas a conformation can
or the formation of the syn invertomer, H-NMR ex-
1
periments were carried out in deuterated acetone at
different temperatures. When the temperature de-
creased to −40°C, poor signal resolution was observed
and no other species could be detected.
For complex 2, an H,H-COSY experiment was car-
ried out because of the complexity of the 1H-NMR
spectra. The distribution of the signals of the coordi-
nated COD and dithioether is similar to complex 1
which indicates that this complex has also a C2
symmetry.
The structure of the complex 2 was confirmed by
X-ray crystallography. An ORTEP drawing (thermal el-
lipsoids of 50% probability for the non-hydrogen
atoms) is shown in Fig. 6. Selected bonds and angles
are listed in Table 1. This compound crystallizes in the
chiral space group P212121, and it is optically active. In
the crystal studied, the asymmetric unit was found to
consist of two molecules of the chiral cation, with two
counteranions. The rhodium atom has a slightly dis-
torted square-planar environment. The metal atom is
bonded to a cyclooctadiene molecule coordinated
through both olefinic double bonds, and to the
DIOSiPr2 ligand coordinated via both sulphur atoms
1
Fig. 4. H-NMR spectra of complex 2 in the methylenic region of the
coordinated DIOSMe2 at 40°C.
Fig. 5. Possible diastereoisomers for the new complexes.

26
A. Orejo´n et al. / Journal of Organometallic Chemistry 559 (1998) 23–29
(1995 (s), 2019(s) and 2092(s) for [Rh(CO)2
(DIOSMe2)]n(ClO4)n and 2017(s), 2052(s) and 2092(s) for
[Rh(CO)2(DIOSiPr2)]n(ClO4)n) which are characteristic
of tetracarbonylated dinuclear rhodium(I) complexes
[13]. When equivalent conductivities of the tetracarbony-
lated complex 4 were measured in acetone solutions at
various concentrations, the slopes for the Onsager’s
equation were characteristic of 2:1 electrolytes [14].
The conductivity study and the molecular weight of the
carbonylated complex with the DIOSMe2 ligand could
not be determined because of its instability but,
by comparison with complex 4, we suggest it is a
dinuclear species. In conclusion, the complexes can
be formulated as [(CO)2Rh(v-DIOSR2)2Rh(CO)2]
(ClO4)2.
2.2. Styrene hydroformylation
It has been previously reported that cationic complexes
containing dithioether chiral ligands [Rh(COD)
(BINASMe2)]A, A=BF4−, ClO4− behave as catalyst
precursors in the hydroformylation of styrene with-
out the addition of phosphorous ligands and provide
regioselectivities as high as 86% and e.e. up to 15% ([7]a).
In this work, the mononuclear cationic rhodium
Fig. 6. ORTEP structure for complex 2 showing thermal ellipsoids at
50% probability.
i
complexes containing DIOSR2, R=Me, Pr, dithioe-
ther ligands have been used as catalyst precursor
The Rh–S and Rh–C distances (averages 2.360 and
˚
2.178 A respectively) are similar to other complexes with
cyclooctadiene ligands trans to dithiolate bridged lig-
ands. Thus, distances in the range 2.35–2.39 A were
Table 1
Selected
[Rh(COD)(DIOSiPr2)]ClO4 (2) with e.s.d.s in parentheses
˚
(A)
˚
bond
distances
and
angles
(°)
for
found for the complexes [Rh2(v-S(CH2)nS)(COD)2] (n=
2 and 3) [12]. Related thioether complexes [Rh(NBD)2
(SEt2)]+ ([6]a,f) and [Rh(CO)2(tBuSCHꢀCHStBu)]+
Rh–S(1)
2.363(4)
2.361(4)
C(11)–C(11B)
C(12)–C(12A)
1.55(3)
1.28(5)
1.56(3)
1.55(2)
1.53(2)
1.42(2)
1.38(2)
1.35(2)
1.60(3)
1.49(4)
1.79(6)
1.43(2)
99.0(6)
38.4(6)
82.7(6)
86.5(5)
166.6(5)
167.8(5)
96.0(5)
107.0(5)
110.5(6)
94.51
Rh–S(2)
˚
have Rh–S distances from 2.3643 to 2.500 A.
Rh–C(6)
Rh–C(1)
Rh–C(2)
2.140(13) C(12)–C(12B)
2.168(14) C(13)–C(15)
2.178(14) C(14)–C(16)
The shortest intermolecular distance between two
˚
different molecules is 8.35 A. This distance indicates that
Rh–C(5)
S(1)–C(11)
S(1)–C(13)
S(2)–C(12)
S(2)–C(14)
C(11)–C(11A)
C(1)–C(2)
C(6)–Rh–C(1)
C(1)–Rh–C(2)
C(1)–Rh–C(5)
C(6)–Rh–S(2)
C(2)–Rh–S(2)
C(6)–Rh–S(1)
C(2)–Rh–S(1)
S(2)–Rh–S(1)
C(11)–S(1)–Rh
C(12)–S(2)–Rh
2.19(2)
1.84(2)
1.81(2)
1.85(2)
1.81(2)
1.54(3)
1.40(2)
82.6(6)
37.7(7)
90.4(7)
153.0(5)
87.0(5)
95.9(5)
153.6(5)
89.57(14)
114.1(6)
111.5(7)
C(15)–O(1)
C(16)–O(2)
O(1)–C(17)
O(2)–C(17)
C(17)–C(18)
C(17)–C(19)
C(5)–C(6)
C(6)–Rh–C(2)
C(6)–Rh–C(5)
C(2)–Rh–C(5)
C(1)–Rh–S(2)
C(5)–Rh–S(2)
C(1)–Rh–S(1)
C(5)–Rh–S(1)
C(13)–S(1)–Rh
C(14)–S(2)–Rh
M(1)–Rh–M(2)
there is no interaction between the metal atoms of
different molecules.
i
The relative configuration of the Pr groups is anti as
the NMR data showed.
Bubbling carbon monoxide at room temperature
through
dichloromethane
solutions
of
[Rh(COD)(DIOSR2)]ClO4 (R=Me, iPr) complexes gave
the corresponding carbonylated species (Eq. (2)). The
elemental analyses matched the stoichiometry
[Rh(CO)2(dithioether)]n(ClO4)n.
4CO
2[Rh(COD)(DIOSR2)]CPO4 “
“[(CO)2Rh(m-DIOSR2)2Rh(CO)2](ClO4)2+2COD
C(14)–S(2)–C(12) 103.6(9)
C(13)–S(1)–C(11) 101.8(8)
R=Me
R=iPr
3
4
S(1)–Rh–M(1)
S(2)–Rh–M(2)
97.23
80.29
S(1)–Rh–M(2)
S(2)–Rh–M(2)
167.89
173.96
(2)
The solid state and solution FT-IR spectra of these
complexes show three w(CO) stretching frequencies
M(1) and M(2) represent the midpoints of the C(5)–C(6) and C(1)–
C(2) olefin double bonds.

A. Orejo´n et al. / Journal of Organometallic Chemistry 559 (1998) 23–29
27
Table 2
Styrene hydroformylation at 30 atm and 65°Ca
Entry
Precursor
L
t (h)
%Cbald
%2-PP/3-PPc
% e.e.d
1
2
3
4
5
6
1
1
2
2
—
14
14
22
4
7
2
57
94
74
99
96
78
69/31
70/30
72/28
71/29
74/26
63/27
3 (S)
4 (S)
6 (S)
6 (S)
4 (S)
—
3 (+)-DIOSMe2
—
3 (−)-DIOSiPr2
4 (−)-DIOSiPr2
—
[Rh(acac)(CO)2]
[Rh(acac)(CO)2]
a Reaction conditions: styrene (10 mmol), complex (0.05 mmol), tetrahydrofuran (7.5 ml), CO/H2=1.
b Aldehyde conversion measured by chromatography integral ratio with no addition of internal standard.
c 2-PP: 2-phenylpropanal, 3-PP: 3-phenylpropanal.
d % ee was mesured by chiral gas chromatography on the 2-phenylpropanol obtained by reducing the aldehydes with LiAlH4.
in the hydroformylation of styrene in the form of
isolated rhodium sulphur modified precursors. The con-
version and selectivity results are shown in Table 2.
When the [Rh(COD)(DIOS Me2)]ClO4 (1) and
[Rh(COD)(DIOSiPr2)]ClO4 (2) are used as catalyst pre-
cursors at 30 bar and 65°C, the regioselectivity in
2-phenylpropanal is about 70% (entries 1 and 3).
The addition of a three-fold excess of free dithioether
ligand, dithioether/Rh ratio=4, (entries 2 and 4) in-
creases the conversion into aldehydes. The conversion is
practically total for the precursor 2 containing (−)-
DIOSiPr2 in 4 h. However, regioselectivities remain in
the range of 70% in 2-phenylpropanal and are only
slightly higher.
Although values of enantiomeric excess are very low,
the precursor containing the (−)-DIOSiPr2 provides
higher e.e. than the corresponding methyl dithiother
derivatives.
Experiment 5 was carried out in order to find out if
the behaviour of the cationic isolated precursor system
was the same as the species formed in situ by adding
DIOSR2 to the rhodium precursor [Rh(acac)(CO)2].
When four mols of (−)-DIOSiPr2 were added
(dithioether/Rh ratio=4) to the [Rh(acac)(CO)2] com-
plex, the conversion and regioselectivities were practi-
cally the same.
For comparison purposes, an experiment using
[Rh(acac)(CO)2] without dithiother ligand was carried
out to give lower regioselectivity (entry 6). This indi-
cates that the active species are modified by the
dithioether ligand.
The activities and regioselectivities obtained using
these dithioether-modified rhodium systems are in fact
lower than using other Rh/diphosphine systems ([7]b).
However, the regioselectivity obtained by these systems
is higher than the regioselectivity obtained by the
[Rh(v-OMe)(COD)]2/2DIOP system, in the same con-
ditions, which provide 62% in 2-phenylpropanal [9]. It
is also higher than the regioselectivity obtained with the
[RhH(CO)(PPh3)3] system using DIOP as auxiliary lig-
and which is about 60%.
In comparison with the results obtained using the
precursor system based on the dithiolate bridged
[Rh2(v-DIOS)(COD)2] complex without phosphorous
ligand, which in the same conditions achieves 64% of
the regioselectivy in 2-phenylpropanal with the cationic
dithioether precursor, conversions are lower but re-
gioselectivities higher [9]. Although the introduction of
the R substituents in the S-atom may favour chiral
induction, the enatioselectivities are also low and only
the regioselectivities are higher.
Although in the NMR studies were not observed
different diastereoisomers, the low e.e. obtained in the
hydroformylation of styrene could be attributed to the
formation
of
an
unfavourable
mixture
of
diastereomeric rhodium complexes. This may be due to
the configurational lability of the S-stereocenters under
hydroformylation conditions.
3. Experimental
All the rhodium complexes were synthesized using
standard Schlenk techniques under a nitrogen atmo-
sphere. Solvents were distilled and deoxygenated before
use. The complexes [Rh(COD)2]ClO4 [10], [Rh(acac)
(CO)2] [15] and [Rh(v-OMe)(COD)]2 [16] and the
i
dithioethers DIOSR2 (R=Me, Pr and Ph) ([8]b), [17],
were prepared using literature methods. All other
reagents were used as commercially supplied. Elemental
analyses were performed on a Carlo-Erba microana-
lyzer. The IR spectra were obtained using a Nicolet
5ZDX-FT spectrophotometer and a Prospect spec-
1
trophotometer. H-NMR spectra were recorded on a
Varian Gemini 300 MHz spectrophotometer, and the
chemical shifts are quoted in ppm downfield from
internal SiMe4. FAB mass spectrometry was performed
on a VG Autospect in a nitrobenzyl alcohol matrix.
Gas chromatography analyses were performed on a

28
A. Orejo´n et al. / Journal of Organometallic Chemistry 559 (1998) 23–29
Hewlet Packard Model 5890, a gas chromatograph with
a flame ionization detector using a 25 m ×0.2 mm of
internal diameter in capillary column (Ultra 2). The
enantiomeric excesses of the corresponding alcohols
obtained as previously described [9] were measured on
the same equipment using a 50 m ×0.25 mm of
internal diameter in capillary column (FS-cyclodex i-I/
P) The catalytic experiments were carried out according
to a previously described standard procedure [9].
COD); 36.06 (S–CH–CH3, DIOSiPr2); 38.32 (CH2,
DIOSiPr2); 78.51 (–CH–, DIOSiPr2); 107.43 (–CH–,
COD); 111.22 (–CH–, COD); 128.70 (–C–CH3,
DIOSiPr2). F.A.B.: m/z=489 [M–ClO4].
3.3. Preparation of [Rh(CO)2(DIOSMe2)]2(ClO4)2 (3)
Carbon monoxide was bubbled through a solution of
[Rh(COD)(DIOSMe2)]ClO4 (50 mg, 0.094 mmol) in
dichloromethane for 10 min. The initial yellow solution
turned orange. Adding diethyl ether gave an orange
precipitate which was filtered off under nitrogen,
washed with diethyl ether and dried in vacuo (24.0 mg,
53.3% yield). (Found: C, 27.00; H, 4.50; S, 12.50. Calc.
for C22H36S4O16Rh2Cl2: C, 27.50; H, 3.77; S, 13.34). IR
(KBr): 2005, 2041, 2099; (CH2Cl2): 1995, 2019, 2092
3.1. Preparation of [Rh(COD)(DIOSMe2)]ClO4.1/2
CH2Cl2 (1)
A slight excess of the DIOSMe2 ligand (138 mg, 0.62
mmol) was added to a solution of [Rh(COD)2]ClO4
(200 mg, 0.48 mmol) in dichloromethane. The orange
solution turned yellow. After stirring at room tempera-
ture for 10 min, diethyl ether was added to give a
yellow precipitate of 1 which was filtered off and dried
under vacuum (247 mg, 97% yield). (Found: C, 36.39;
H,5.41; S, 11.65. Calc for C35/2H31S2O6RhCl2: C, 36.50;
cm−1
.
3.4. Preparation of [Rh(CO)2(DIOSiPr2)]2(ClO4)2 (4)
Carbon monoxide was bubbled through a solution of
[Rh(COD)(DIOSiPr2)]ClO4 (97 mg, 0.16 mmol) in te-
trahydrofuran for 20 min. A yellow precipitate ap-
peared inmediately which was filtered off, washed with
diethyl ether and dried in vacuo (60.3 mg, 68% yield).
(Found: C, 33.59; H, 5.08; S, 11.98. Calc. for
C30H52S4O16Rh2Cl2: C, 33.56; H, 4.88; S, 11.94). IR
(KBr): 2082, 2009, 1974; (CH2Cl2): 2105, 2052, 2017
1
H, 5.43; S, 11.14). H-NMR (CDCl3): l 2.05 (m, 2H,
–CH2–, COD); 2.11 (m, 2H, –CH2–, COD); 2.58 (m,
4H, –CH2–, COD); 4.55 (m, 2H, –CH–, COD); 4.65
(m, 2H, –CH–, COD); 1.45 (s, 6H, CH3–, DIOSMe2);
2.38 (s, 6H, –S–CH3, DIOSMe2); 3.00 (m, 4H, –CH2–,
DIOSMe2); 4.42 (m, 2H, –CH–, DIOSMe2); 5.30 (s,
1H, CH2Cl2). 13C-NMR (CD2Cl2): l 17.34 (–S–CH3,
DIOSMe2); 27.01 (CH3–, DIOSMe2); 30.69 (–CH2–,
COD); 31.54 (–CH2–, COD); 41.43 (–CH2–,
DIOSMe2); 79.04 (–CH–, DIOSMe2); 91.17 (–CH–,
COD); 92.03 (–CH–, COD); 111.18 (–C–CH3,
DIOSMe2). F.A.B.: m/z=433 [M–ClO4].
1
cm−1. H-NMR (Aceton-D): l 1.41 (s, 6H, –C–CH3,
DIOSiPr2); 1.51 (m, 12H, S–CH–CH3, DIOSiPr2); 3.38
(t, 2H, –CH2–, DIOSiPr2); 3.67 (bd, 2H, –CH2–,
DIOSiPr2); 3.86 (m, 2H, S–CH–CH3, DIOSiPr2); 4.62
(m, 2H, –CH–CH2–, DIOSiPr2). F.A.B.: m/z=687
i
[M+ −4 Pr2−1 Me]; m/z=437 [(M/2)H+]; m/z=
3.2. Preparation of [Rh(COD)(DIOSiPr2)]ClO4.1/2
CH2Cl2 (2)
379 [Rh+DIOSiPr2−H]. Conductivity in aceton
Leq=164.174–1207.511 ꢀCe; r= −0.991.
A slight excess of the DIOSiPr2 ligand (43.2 mg, 0.15
mmol) was added to a solution of [Rh(COD)2]ClO4 (50
mg, 0.12 mmol) in dichloromethane. The orange solu-
tion turned yellow. After stirring at room temperature
for 10 min, diethyl ether was added to give a yellow
precipitate of 2 which was filtered off and dried under
vacuum (64.7 mg, 92% yield). (Found: C, 40.20; H,
6.19; S, 10.00. Calc for C43/2H39S2O6RhCl2: C, 40.68; H,
3.5. Crystal structure determination for compound 2
Suitable crystals of complex 2 were grown by slowly
diffusing diethyl ether into a solution of the complex in
CH2Cl2 and mounted on a glass fibre.
The data were collected and processed at room tem-
perature on a Mar Research image plate scanner, and
graphite-monochromated Mo Kh radiation was used to
measure 95 2° frames, 360 s per frame.
1
6.20; S, 10.09). H-NMR (CDCl3): l 1.44 (s,12H, S–
CH–CH3, DIOSiPr2); 1.48 (s, 6H, –C–CH3,
DIOSiPr2); 2.05 (m, 2H, –CH2–, COD); 2.40 (m, 4H,
–CH2–, COD); 2.65 (m, 2H, –CH2–, COD); 2.88 (t,
2H, –CH2–, DIOSiPr2); 3.28 (bd, 2H, –CH2–,
DIOSiPr2); 3.41 (m, 2H, S–CH–CH3, DIOSiPr2); 4.50
(m, 2H, –CH–, COD); 4.72 (m, 2H, –CH–CH2–,
DIOSiPr2); 4.70 (m, 2H, –CH–, COD); 5.30 (s, 1H,
CH2Cl2). 13C-NMR (CDCl3): l 21.17 (S–CH–CH3,
DIOSiPr2); 22.76 (S–CH–CH3, DIOSiPr2); 26.95 (–C–
CH3, DIOSiPr2); 29.49 (–CH2–, COD); 32.29 (–CH2–,
2×[RhS2C21H34O2.ClO4.1/2CCl2], M=1252.83, or-
thorhombic, a=9.415(5), b=14.133(5), c=42.182(5)
3
˚
˚
A, U=5612.8 A , space group P212121 (no. 19), Z=4,
Dc=1.483 g cm−3, F(000)=2576. Orange, crystal di-
mensions 0.22×0.14×0.30 mm, v(Mo Kh)=9.80
cm−1
.
The XDS package was used to give 3998 unique
reflections [merging R=0.0992]. The heavy atoms were
found from the Patterson map using the SHELX86 pro-
gram and refined subsequently from successive differ-

A. Orejo´n et al. / Journal of Organometallic Chemistry 559 (1998) 23–29
29
Table 3
Crystal Data for compound 2
Acknowledgements
We thank the Ministerio de Educacio´n y Ciencia
and the Generalitat de Catalunya for financial sup-
port (QFN-95-4725-C03-2; CICYT-CIRIT). This work
was supported in part by the Commision of the Eu-
ropean Communities (Contract n°CI1*-CT93-0329).
Empirical formula
Formula weight
Temperature
Wavelength
Crystal system
Space group
2×[RhS2C21H34O2.ClO4.1/2CCl2]
1252.83
293 K
0.71069 A
Orthorhombic
P212121
˚
a=9.41(5) A
Unit cell dimensions
˚
b=14.13(5) A
˚
c=42.18(5) A
5612.8 A
References
3
˚
Volume
Z
4
[1] P.A. Chaloner, M.A. Esteruelas, F. Joo, L.A. Oro, in: Homoge-
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P.M. Maitlis, J. Chem. Soc. Dalton (1978) 857.
Density (calculated)
Absorption coefficient
F(000)
Crystal size
q range for data collection
Index ranges
Reflections collected
Independent reflections
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I\2|(I)]a
R indices (all data)a
1.483 g/cm3
9.80 cm−1
2576
0.22×0.14×0.30 mm
2.04–22.61°
05h510, 05k514, −145l545
19 375
3998 [R(int)=0.0992]
Full-matrix least-squares on F2
3984/0/595
[5] R. Uso´n, L.A. Oro, R. Sariego, M. Valderrama, C. Rebullida, J.
Organomet. Chem. 197 (1980) 87.
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Chem. Soc. Dalton Trans. (1984) 2665.
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Gladiali, J. Chem. Soc. Chem. Commun. (1993) 1833. (b) S.
Gladiali, J.C. Bayo´n, C. Claver Tetrahedron Aymmetry 6 (1995)
1453.
1.094
R1=0.0699, wR2=0.1712
R2=0.0856, wR2=0.1927
Absolute structure parameter 0.05(9)
Extinction coefficient
Largest diff. peak and hole
0.0043(6)
0.696 and −0.559 eA
−3
˚
a R1=SꢁFoꢂ−ꢂFcꢁ/SꢂFoꢂ; wR2=[Sw(F2o−Fc2)/Sw(Fo2)2]1/2
;
w=1/
[|2(Fo2)+(0.1025P)2+21.43P] where P=(max(Fo2,0)+2F2c)/3).
[8] (a) R. James, R.S. MacMillan, R.H. Morris, D.K.W. Wang,
Advanc. Chem. Ser., 167 (1978) 123. (b) R. James, R.S. MacMil-
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S. Castillo´n, C. Claver, Tetrahedron Aymmetry 6 (1995) 1885.
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(1975) 169.
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(1984) 1.
[12] A.M. Masdeu, A. Ruiz, S. Castillo´n, C. Claver, P.B. Hitchcock,
P. Chaloner, C. Bo, J.M. Poblet, P. Sarasa, J. Chem. Soc. Dalton
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J.J. Bonnet, Ph. Kalck, R. Poilblanc, Inorg. Chem. 16 (1977) 1514.
[14] R.D. Feltham, R.G. Hayter, J. Chem. Soc. A (1964) 4587.
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[16] R. Uso´n, L.A. Oro, J. Cabeza, Inorg. Synth. 23 (1985) 126.
[17] M. Die´guez, A. Orejo´n, A.M. Masdeu-Bulto´, R. Echarri, S.
Castillo´n, C. Claver, A. Ruiz, J. Chem. Dalton Trans. (1997) 4611.
ence Fourier maps using SHELXL, by full-matrix least
squares of 595 variables, to a final R-factor of 0.0699
for 3984 reflections with [Fo]\4|(Fo). All atoms were
revealed by the Fourier map difference. Non hydro-
gen atoms were refined anisotropically. Hydrogen
atoms were placed geometrically and refined with a
fixed isotropic atomic displacement parameter. R val-
ues: R1 ([Fo]\4|(Fo), for 3984 reflections)=0.0699;
R2 (all data)=0.0856. The weighting scheme w=1/
[|2(F2o)+(0.1025P)2+21.43P]
where
P=(max
(F2o,0)+2Fc2)/3) with |(Fo) from counting statistics
gave satisfactory agreement analyses. Large diff. peak
and hole in the final difference map: 0.696 and −
0.559 eA−3. Data collection parameters including R1
˚
([I\2|(I)]) and R2 (all data) values are summarized
in Table 3.
.